1. Field of the Invention
This invention relates to a toner collection device and, in particular, to a device for collecting the toner which has been removed from the surface of a photosensitive member after image transfer for use in an electrophotographic copying machine.
2. Descripion of the Prior Art
In a transfer type electrophotographic copying machine, some toner will remain on the surface of the photosensitive member after the image transfer step, and such residual toner must be removed from the surface prior to the initiation of the next following copying process. The residual toner thus removed is then collected in a toner collecting container which is detachably installed in the copying machine.
Such a toner collecting container is usually in the shape of a bottle or box provided with an opening at its top. The toner removed from the photosensitive member is guided into the opening and thus the toner will fall by its own weight toward the bottom of the container. However, since the toner will fall onto the same point, there will soon be formed a heap and its apex will block the opening to hinder further collection of toner even if there is still some room inside the container.
One prior art approach to cope with this problem is to make the toner falling distance long. However, this approach is not always advantageous because it requires to make a vertically elongated container which may not be used in compact machines such as desk-top type machines. Another prior art approach is to maintain the toner collecting container in constant vibration so as to decrease the height of the heap by spreading the collected toner sideways. This second approach, however, creates a noise problem and it requires a significant amount of power to substantially flatten the toner surface inside the container. Furthermore, design of the container is rather limited because an opening must be usually located at the center in order to attain efficient spreading of the collected toner. Even in this second approach, there still remains difficulty in using a laterally elongated container.
It is desirous to provide such a toner collecting container detachably because it will become full when the copying operation is carried out repetitively. Thus, it is desirous to provide a structure which will indicate the state that the container has become full to the operator. Furthermore, when the container is provided to be detachable, it is desirous that the operator be warned if no container is installed in position in order to prevent the toner removed from the photosensitive member from being scattered in the machine. None of the prior art devices is satisfactory in meeting all these conditions, and, thus, there has been a need for providing an improved toner collecting device.